Superconducting Composite Wire - Material Information

Superconducting composite wires composed of niobium-titanium (Nb–Ti) alloys embedded in a copper matrix are the cornerstone of low-temperature superconducting (LTS) magnet technology. These wires exhibit exceptional current-carrying capacity and mechanical stability, making them critical components in MRI systems, particle accelerators, and fusion devices. Their composite architecture combines the high critical field of Nb–Ti with the thermal and electrical stability provided by copper.

Material Overview

The Nb–Ti/Cu composite wire structure typically consists of Nb–46.5 wt% Ti filaments encased in a high-purity copper stabilizer, sometimes with an intermediate niobium diffusion barrier to prevent intermetallic formation. The alloy’s superconducting transition temperature (T_c) is around 9.2 K, with upper critical magnetic fields (B_c2) reaching up to 10–11 T at 4.2 K (Colling et al., 1977). The critical current density (J_c) depends strongly on filament diameter and heat treatment; optimized multifilamentary wires achieve J_c ? 2.0×10⁵ A·cm?² at 5 T (Itoh & Sasaki, 1995). Incorporating Nb barriers and Cu stabilizers ensures excellent electrical contact and reduces eddy current losses. Composite designs using Nb–Ti barriers demonstrate strong resistance to diffusion at annealing temperatures up to 850 °C while retaining superconducting integrity (Ková? et al., 2010). Reinforcement with Cu–Nb or Nb–Ti cores also improves mechanical durability, providing yield strengths exceeding 100 MPa at cryogenic temperatures (Sun et al., 2012).

Applications and Advantages

Nb–Ti/Cu composite wires are extensively employed in high-field superconducting magnets for research and medical systems. Their unique balance of high J_c, ductility, and resistance to mechanical strain makes them ideal for winding large solenoids and coils in fields up to 10 T. According to Sun et al. (2013), Nb–Ti-reinforced MgB₂ wires achieved J_ce > 7.9×10³ A·cm?² at 35 K, demonstrating versatility across hybrid superconducting applications. These wires are also used in cryogenic power devices and energy storage systems where consistent performance under repeated mechanical loading is essential. Ongoing material optimization continues to enhance conductor uniformity, reduce interfacial resistance, and extend operating life under high magnetic stress.

Goodfellow Availability

Goodfellow provides Nb–Ti/Cu superconducting composite wires in research and industrial grades. These materials combine high superconducting current density with robust mechanical and oxidation resistance for advanced cryogenic and magnetic applications. Explore superconducting materials and other precision-engineered metals through the Goodfellow product finder.

References

• Colling, D. A., de Winter, T., McDonald, W. K., & Turner, W. C. (1977). Superconducting performance of production NbTi alloys. IEEE Transactions on Magnetics, 13(1), 104–109.
• Itoh, I., & Sasaki, T. (1995). Critical current density of superconducting NbTi/Nb/Cu multilayer composite sheets. Cryogenics, 35(6), 373–377. https://doi.org/10.1016/0011-2275(95)00033-P
• Ková?, P., Hušek, I., Melišek, T., Kopera, L., & Reissner, M. (2010). Cu-stabilized MgB₂ composite wire with an NbTi barrier. Superconductor Science and Technology, 23(2), 025014. https://doi.org/10.1088/0953-2048/23/2/025014
• Sun, Y., Wang, Q., Fang, Y., Xiong, X., Qi, M., Liang, M., Yan, G., Sulpice, A., & Zhang, P. (2012). Mechanical and superconducting properties of 6-filament MgB₂ wires reinforced by Cu, Cu–Nb and NbTi. Physica C: Superconductivity and Its Applications, 478, 45–52. https://inis.iaea.org/records/nxqjv-66g21
• Sun, Y. Y., Zhang, P. X., Wang, Q. Y., Qi, M., Fang, Y., Jiao, G. F., & Yan, G. (2013). Mechanical and superconducting properties of NbTi-reinforced MgB₂ wires. Materials Science Forum, 745–746, 173–177. https://doi.org/10.4028/www.scientific.net/MSF.745-746.173